The present invention relates generally to testing the characteristics of elastomeric weatherstrips. In particular the invention is concerned with a method and apparatus for determining the sliding resistance between an extruded elastomeric weatherstrip and a glass section being passed through a channel defined by the weatherstrip.
Extruded elastomeric weatherstrips are commonly used to provide sealing between the edges of openings of motor vehicle bodies and closure elements for those openings. These weatherstrips are particularly well suited for providing protection from air, water, and dust passing through window seams. To perform effectively, the weatherstrips must be manufactured to given specifications.
An elastomeric weatherstrip designed for use between a window and a door pillar section of a motor vehicle body typically includes a channel for guiding the window and a sealing section for providing sealing between the two components. An important characteristic of such an elastomeric weatherstrip, is the amount of resistance that it provides a window being urged through the channel while the window is being either opened or closed. This is referred to as sliding resistance and is equivalent to the friction force generated between the surface of the weatherstrip that defines the channel and the surface of the glass section being urged through the channel.
If the channel is too narrow, sliding resistance will be high and the force required to drive the window through the channel will be excessive. This results in the task of manually opening or closing the window being unduly burdensome to the operator. In he case of motor-driven windows, too high sliding resistance between the window and the channel will prevent the motor from closing the window.
If the channel is too wide, the sliding resistance between the window and the channel will be low but the sealing provided therebetween will be poor. It is important therefore, that the channel defined by a weatherstrip as used on the pillar section of an automobile door frame be properly formed so that effective sealing is provided between the window and the door pillar section but excessive force is not required to drive the window through the channel.
It is, therefore, an object of the present invention to provide a method and apparatus for simply and economically measuring sliding resistance. It is another object of the present invention to enable a manufacturer of elastomeric weatherstrips to monitor the sliding resistance of manufactured weatherstrips.